- From: Eric Rescorla <ekr@rtfm.com>
- Date: Wed, 21 Nov 2018 13:51:27 -0800
- To: IESG <iesg@ietf.org>
- Cc: httpbis-chairs@ietf.org, Mark Nottingham <mnot@mnot.net>, draft-ietf-httpbis-expect-ct@ietf.org, HTTP Working Group <ietf-http-wg@w3.org>
- Message-ID: <CABcZeBPd8qbQ9_NZTTuzexka1FUjZwjpLxyhfz0L0nnPBmGHng@mail.gmail.com>
Following up, I don't see any response to these comments. -Ekr On Thu, Sep 13, 2018 at 7:22 AM Eric Rescorla <ekr@rtfm.com> wrote: > I have one other non-blocking comment: Why is this document Experimental? > People are already deploying CT without this. It seems like PS would make > more sense or Informational. > > Alexey, I leave it to you. > -Ekr > > > On Wed, Sep 12, 2018 at 4:12 PM, Eric Rescorla <ekr@rtfm.com> wrote: > >> Eric Rescorla has entered the following ballot position for >> draft-ietf-httpbis-expect-ct-07: Discuss >> >> When responding, please keep the subject line intact and reply to all >> email addresses included in the To and CC lines. (Feel free to cut this >> introductory paragraph, however.) >> >> >> Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html >> for more information about IESG DISCUSS and COMMENT positions. >> >> >> The document, along with other ballot positions, can be found here: >> https://datatracker.ietf.org/doc/draft-ietf-httpbis-expect-ct/ >> >> >> >> ---------------------------------------------------------------------- >> DISCUSS: >> ---------------------------------------------------------------------- >> >> Rich version of this review at: >> https://mozphab-ietf.devsvcdev.mozaws.net/D4579 >> >> >> This generally seems like a sound mechanism, but I believe there are >> some points here that are sufficiently unclear they might create >> interop problems,s o I am balloting DISCUSS. >> >> Most importantly, this document just says you support CT, but that >> creates a potential interop problem if say 6962-tris had a different >> way of delivering CT information or a different syntax. I'm not saying >> you need a version here, but you need to indicate that it's not >> forward-looking. >> >> Also, see below. >> >> DETAIL >> S 2.4. >> > beginning an HTTP conversation over the TLS channel. >> > >> > If a connection to a Known Expect-CT Host violates the UA's CT >> policy >> > (i.e., the connection is not CT-qualified), and if the Known >> Expect- >> > CT Host's Expect-CT metadata indicates an "enforce" configuration, >> > the UA MUST treat the CT compliance failure as an error. >> >> Is this supposed to be a hard failure, as with HSTS. If not, how does >> it interact with HSTS's hard failure reqs. >> >> >> S 3.1. >> > (This may differ from the value of the >> "served-certificate-chain" >> > key.) The value is provided as an array of strings, which MUST >> > appear in the order matching the chain that the UA validated; >> each >> > string in the array is the Privacy-Enhanced Mail (PEM) >> > representation of each X.509 certificate as described in >> > [RFC7468]. >> >> What happens if you try to construct multiple paths? >> >> >> S 3.1. >> > does not have or does not trust the public key of the log >> from >> > which the SCT was issued), "valid" (indicating that the UA >> > successfully validated the SCT as described in Section 5.2 of >> > [RFC6962] or Section 8.2.3 of [I-D.ietf-trans-rfc6962-bis]), >> or >> > "invalid" (indicating that the SCT validation failed because >> > of, e.g., a bad signature). >> >> Is "invalid" anything other than the specific cases listed above? >> >> >> ---------------------------------------------------------------------- >> COMMENT: >> ---------------------------------------------------------------------- >> >> >> > allows web host operators to instruct user agents to expect valid >> > Signed Certificate Timestamps (SCTs) to be served on connections to >> > these hosts. Expect-CT allows web host operators to discover >> > misconfigurations in their Certificate Transparency deployments and >> > ensure that misissued certificates accepted by UAs are discoverable >> > in Certificate Transparency logs. >> >> I don't believe that it does this. Consider a client which simply did >> not support CT, then it would (a) accept a misissued certificate that >> (b) was not discoverable >> >> >> S 2.1.1. >> > >> > Figure 2: Syntax of the report-uri directive value >> > >> > "absolute-URI" is defined in Section 4.3 of [RFC3986]. >> > >> > Hosts may set "report-uri"s that use HTTP or HTTPS. If the scheme >> in >> >> Why are you allowing HTTP? >> >> >> S 2.3.2. >> > the "enforce", "max-age", or "report-uri" header field value >> > directives convey information different from that already >> > maintained by the UA. If the "max-age" directive has a value of >> > 0, the UA MUST remove its cached Expect-CT information if the >> host >> > was previously noted as a Known Expect-CT Host, and MUST NOT >> note >> > this host as a Known Expect-CT Host if it is not already noted. >> >> As noted above, I think you need to clear the cache when you upgrade >> to a potentially incompatible CT version, or otherwise reconfigure the >> client. >> >> >> S 2.3.2.1. >> > this host as a Known Expect-CT Host if it is not already noted. >> > >> > 2.3.2.1. Noting Expect-CT >> > >> > Upon receipt of the Expect-CT response header field over an error- >> > free TLS connection (including the validation adding in Section >> 2.4), >> >> s/adding/added/? >> >> >> S 2.3.2.1. >> > host's domain name and its associated Expect-CT directives in non- >> > volatile storage. >> > >> > To note a host as a Known Expect-CT Host, the UA MUST set its >> Expect- >> > CT metadata given in the most recently received valid Expect-CT >> > header field, as specified in Section 2.3.2.2. >> >> This seems ungrammatical. Set it where? >> >> >> S 2.3.2.2. >> > >> > 2.3.2.2. Storage Model >> > >> > If the substring matching the host production from the Request-URI >> > (of the message to which the host responded) does not congruently >> > match an existing Known Expect-CT Host's domain name, per the >> >> I would say "exactly match" rather than "congruently match" unless >> this ia term of art somewhere. >> >> >> S 2.3.2.2. >> > understands them, the UA MAY note them as well. >> > >> > UAs MAY set an upper limit on the value of max-age, so that UAs >> that >> > have noted erroneous Expect-CT hosts (whether by accident or due to >> > attack) have some chance of recovering over time. If the server >> sets >> > a max-age greater than the UA's upper limit, the UA MAY behave as >> if >> >> This MAY seems out of place, given that you already said MAY. >> >> >> S 2.4. >> > >> > When a UA connects to a Known Expect-CT Host using a TLS >> connection, >> > if the TLS connection has no errors, then the UA will apply an >> > additional correctness check: compliance with a CT Policy. A UA >> > should evaluate compliance with its CT Policy whenever connecting >> to >> > a Known Expect-CT Host, as soon as possible. However, the check >> can >> >> What does "as soon as possible" mean? >> >> >> S 2.4. >> > terminates the connection due to an Expect-CT failure, this could >> > cause the UA to skip subsequent correctness checks. When the CT >> > compliance check is skipped or bypassed, Expect-CT reports >> > (Section 3) will not be sent. >> > >> > When CT compliance is evaluted for a Known Expect-CT Host, the UA >> >> Nit: evaluated >> >> >> S 2.4.1. >> > "report-uri" (Section 3). >> > >> > 2.4.1. Skipping CT compliance checks >> > >> > It is acceptable for a UA to skip CT compliance checks for some >> hosts >> > according to local policy. For example, a UA may disable CT >> >> Should this be MAY? >> >> >> S 3.1. >> > >> > o "scts": the value represents the SCTs (if any) that the UA >> > received for the Expect-CT host and their validation statuses. >> > The value is provided as an array of JSON objects. The SCTs may >> > appear in any order. Each JSON object in the array has the >> > following keys: >> >> So these just apply to the EE cert? What about CT for the non-EE >> certs? >> >> >> >> >> S 3.1. >> > of, e.g., a bad signature). >> > >> > * The "source" key, with a string value that indicates from >> where >> > the UA obtained the SCT, as defined in Section 3 of [RFC6962] >> > and Section 6 of [I-D.ietf-trans-rfc6962-bis]. The UA MUST >> set >> > the value to one of "tls-extension", "ocsp", or "embedded". >> >> What do these mean? They seem obvious, but you don't say. >> >> >> >
Received on Wednesday, 21 November 2018 21:52:27 UTC